Multi-circuit electrified ceiling grid

ABSTRACT

A suspended ceiling elongate grid tee having a lower flange, a vertical web, and an upper hollow reinforcing bulb, at least some of the flange, web and bulb elements, having relatively flat exposed or accessible surfaces, and a plurality of pairs of conductors attached to said flat surfaces and extending along substantially the full length of the tee whereby grid tee is capable of carrying at least two fully independent DC circuits.

This application claims the priority of U.S. Provisional Application No. 61/118,062, filed Nov. 26, 2008.

The invention relates to suspended ceiling structures and, in particular, to electrification of such ceiling structures.

BACKGROUND OF THE INVENTION Prior Art

Commercial building spaces such as offices, laboratories, light manufacturing facilities, health facilities, meeting and banquet hall facilities, educational facilities, common areas in hotels, apartments, retirement homes, retail stores, restaurants and the like are commonly constructed with suspended ceilings. These suspended ceiling installations are ubiquitous, owing to their many recognized benefits. Such ceilings ordinarily comprise a rectangular open grid suspended by wire from a superstructure and tile or panels carried by the grid and enclosing the open spaces between the grid elements. The most common form of grid elements has an inverted T-shaped cross-section. The T-shape often includes a hollow bulb at the top of the inverted stem of the T-shape. A popular variant of this standard T-shape includes a downwardly open C-shaped channel formed by the lower part of the inverted tee.

Advances in electronics has fed further advances and lead the world into the digital age. This digital movement creates an ever-increasing demand for low voltage direct current (DC) electrical power. This demand would seem to be at least as great in finished commercial space as any other occupied environment. A conventional suspended ceiling has potential to be an ideal structure for distributing low voltage electrical power in finished spaced. Many relatively low power devices are now supported on such ceilings and newer electronic devices and appliances are continuously being developed and adopted for mounting on ceilings.

The ceiling structure, of course, typically overlies the entire floor space of an occupiable area. This allows the ceiling to support electronic devices where they are needed in the occupied space. Buildings are becoming more intelligent in energy management of space conditioning, lighting, noise control, security, and other applications. The appliances that provide these features including sensors, actuators, transducers, speakers, cameras, recorders, in general, all utilize low voltage DC power.

As the use of electronics grows, the consumption of low voltage electrical power likewise grows. This seemingly ever accelerating appetite for DC power presents opportunities for more efficient transformation of relatively high voltage utility power typically found at 110/115 or 220/240 alternating current (AC) volts with which the typical enclosed space is provided. Individual power supplies located at the site of or integrated in an electronic device, the most frequent arrangements today, are often quite inefficient in transforming the relatively high voltage AC utility power to a lower DC voltage required by an electronic device. Typically, they can consume appreciable electric power in a standby mode when the associated electronic device is shut off. It is envisioned that a single DC power source serving the electronic needs of a building or a single floor of a building can be designed to be inherently more efficient since its cost is distributed over all of the devices it serves and because it can take advantage of load averaging strategies.

Thus, grid tees used in suspended ceilings, with little added cost, can provide a medium for electrifying the entire ceiling area, including the space immediately above, the plane of the ceiling space, and the space immediately below the ceiling with low voltage power.

SUMMARY OF THE INVENTION

The invention comprises a grid tee member having a plurality of separate low voltage electrical circuits each effectively running its full length. The circuit conductors can be individually accessed at substantially any point along the length of the tee for receiving or supplying electrical power. Each of the conductors can be joined at the ends of its respective tee to corresponding conductors on other tees to provide full electrification of a suspended ceiling. Ideally, the circuits are each formed by a flat strip of a conductive ink or like coating or a metal foil or tape. The invention lends itself to use with conventional roll formed sheet metal grid tees. The conductive strips can be applied to the strip stock of the tee before, during or after the roll forming process.

The relatively low voltage and power requirements of typical solid state ceiling mounted appliances, enable the strips to be comparatively inexpensive and unobtrusive since they and any related insulating layers require little material content. By making the conductive strips relatively wide, and locating them widely spaced over the exposed or accessible surfaces of the tee permits use of low cost connectors or terminals of loose dimensional tolerances.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view of a generalized conventional grid tee of a first style provided with a first arrangement of longitudinally extending electrical conductors;

FIG. 2 is a cross-sectional view of a generalized conventional grid tee of a second style provided with another arrangement of longitudinally extending electrical conductors;

FIG. 3 is a cross-sectional view of the first style of grid tee with a variation in the arrangement of longitudinally extending electrical conductors;

FIG. 4 is a cross-sectional view of the first style of grid tee with still a further arrangement of longitudinally extending electrical conductors;

FIG. 5 is a cross-sectional view of the second style of grid tee with a still further example of a pattern of longitudinally extending electrical conductors; and

FIG. 6 is yet another example of an arrangement for multiple circuits on the second style of grid tee.

DESCRIPTION OF THE PREFERRED EMBODIMENT

In FIGS. 1-6, two generally conventional styles of suspended ceiling grid tees 10, 11 are represented by their cross-sections. FIGS. 1, 3 and 4 illustrate a two-piece tee 10 having a main body 12, with diverging portions 13 of a horizontal lower flange 14, a double layer vertical stem or web 16, and a hollow reinforcing bulb 17 forming its upper part. A separate cap 15 is assembled on the lower faces of the flange portions 13. FIGS. 2, 5 and 6 illustrate a single piece tee 11 having a lower flange 21 in the form of a downwardly open C-shaped channel, a double layer vertical stem or web 16, and a hollow upper reinforcing bulb 17. The tees 10, 11 can represent both main runners and cross runners, terms used in the art to designate, respectively, long elements (nominally 12 or 10 feet or metric equivalent) joined end-to-end and shorter elements (nominally 2 or 4 feet or metric equivalent) that bridge the space between parallel main runners. Most commonly, the tees 10, 11 are manufactured of prepainted steel strip by roll-forming techniques. It will be understood, however, that other forming techniques such as an extrusion process can be used and other materials such as aluminum or plastics can be used to produce the tees 10, 11.

The figures illustrate electrical conductors 26 in the form of flat strips fixed to various exposed surfaces of the grid tees 10, 11. The conductors 26 in the illustrated examples are relatively flat strips, typically being much thinner than the proportions illustrated in these figures for purposes of illustration. The strips 26 in one economical form are bands or traces of printed conductive ink. Such ink is available commercially from T-Ink, Inc. of New York, N.Y. USA. One convenient way of fabricating the grid tees 10, 11 is to roll form their respective shapes from flat metal stock, typically steel. While the metal stock strip is flat, its eventual exposed surface can be coated with an insulating material by known techniques such as roll coating, spraying, powder coating, or like process using known electrically insulating materials. The side of the sheet stock that will bear the conductive strips 26 is either completely coated with electrically insulating material, or is coated with bands where the conductive strips will be applied. Alternatively, insulating material can be applied locally to the surfaces in question after the tee 10 or 11 has been formed. As another alternative, the conductive strip material where it is a foil or tape can be coated or laminated with an electrically insulating material at least on its side that will face towards the grid tee. In the latter case, for example, an adhesive can be applied to the underside of the insulator of the conductive strip 26 or can be applied to the tee 10 or 11 thereby permitting the conductive strips 26 to be permanently attached to the grid tee.

Over coating or over laminating the conductive strip whether it be a conductive ink trace or a metal foil or tape, is optional, if not preferred. Inspection of FIGS. 1 and 2 reveals that the conductors 26 are attached to generally flat exposed or (in the case of the flange 21 of the tee 11) accessible surfaces of the respective tees 10, 11. As shown in FIGS. 1 and 2, the arrangement or pattern of the conductive strips 26 need not be symmetrical with a central vertical plane through the respective tee 10, 11. It will be understood that in the illustrated arrangements, each of the conductive strips 26 is electrically isolated from the remaining strips on a particular tee 10, 11. Moreover, where the tee 10 or 11 is formed of a metal, such as steel or aluminum, as is typical, the body of the tee can be used as a common pole at a voltage polarity opposite the polarity of voltage applied to one or more conductors 26.

FIGS. 3-6, inclusive, illustrate grid tees 10, 11 on which individual local pairs of conductors 27, 28 are provided. It will be seen that the conductors can be arranged in pairs that are symmetrically disposed on the grid tee about its central vertical plane or can be asymmetrically arranged. Additionally, the pairs of conductors can be either immediately adjacent each other, or can be spaced from one another. For example, in the embodiments of FIGS. 4 and 6, certain pairs of the conductors are on opposite sides of a central vertical plane of the tee. Like the conductors 26 described in connection with FIGS. 1 and 2, the conductors 27, 28 can be provided in a variety of forms including conductive ink traces, metal foils or tapes.

The conductors of each pair 27, 28, will normally be operated at opposite polarities. It will be understood that the individual conductors 26 in the arrangements of FIGS. 1 and 2, and the pairs of conductors 27, 28 in FIGS. 3-6 permit as many independent circuits as conductors 26, or pairs of conductors 27, 28 exist on a given tee 10 or 11. Where desired, the conductors 26, and pairs of conductors 27, 28 can be operated at different voltage levels to satisfy the needs of particular digital or electronic devices. Further, it will be seen, that voltage can be supplied to devices that exist below, at, or above the plane of the ceiling.

It should be evident that this disclosure is by way of example and that various changes may be made by adding, modifying or eliminating details without departing from the fair scope of the teaching contained in this disclosure. The invention is therefore not limited to particular details of this disclosure except to the extent that the following claims are necessarily so limited. 

1. A suspended ceiling elongate grid tee having a lower flange, a vertical web, and an upper hollow reinforcing bulb, at least some of the flange, web and bulb elements, having relatively flat exposed or accessible surfaces, and a plurality of pairs of conductors attached to said flat surfaces and extending along substantially the full length of the tee whereby grid tee is capable of carrying at least two fully independent DC circuits.
 2. A grid tee as set forth in claim 1, wherein said conductors comprise ink strips coated over said flat surfaces.
 3. A grid tee as set forth in claim 1, wherein said tee is a roll-formed sheet metal product.
 4. A grid tee as set forth in claim 3, wherein said conductors are attached to the sheet metal before it is shaped from a flat profile.
 5. A grid tee as set forth in claim 1, wherein said flat conductors are metal foil strips or metal tapes adhesively bonded to the grid tee. 